Wireshark mailing list archives
Re: Sub_dissectors assertion failed
From: Scott <theerickson () gmail com>
Date: Fri, 21 May 2010 19:42:30 -0600
On Fri, May 21, 2010 at 3:18 PM, Guy Harris <guy () alum mit edu> wrote:
So what protocols does your custom protocol run on top of?
For now the custom protocol is a dummy protocol that only contains a 32-bit int and rides on top of the IP protocol rider (*it*). I got the custom protocol to show up in the packet detail window ok, although not how I expected..
And what does dissector_try_port() do? All I could tell is that itreturns a gboolean. It takes, as arguments: 1) a handle for a dissector table that uses integral values as keys (it should really be dissector_try_uint(); the "port" is historical); 2) an integral value to use to select a dissector from that dissector table; 3) a tvbuff_t * that refers to a tvbuff with the data to be dissected by the selected dissector; 4) a packet_info *, which should be the one the dissector calling dissector_try_port() was handed; 5) a proto_tree *, which should be the one the dissector calling dissector_try_port() was handed.
When I called dissector_try_port() from the *it* IP rider protocol like this: dissector_try_port(subdissector_table, hf_[type switch], next_tvb, pinfo, tree) the dummy protocol didn't match correctly. However, when I called it like this: dissector_try_port(subdissector_table, pinfo->destport, next_tvb, pinfo, tree) it matched fine. This doesn't make a lot of sense to me (is it REALLY matching on the port?) because the dummy custom protocol does: dissector_add("[*it*].[type]", [macro], test_handle), which doesn't seem to have anything to do with the port.
I mean *any protocol that runs atop IP* can follow it.Then you want to do what I suggested to find the right dissector for the following protocol - just get the "ip.proto" dissector table and use that.
Because the dummy protocol doesn't have a subdissectors table, the original IP rider protocol needs to call dissector_try_port() again to grab the dissectors for any protocols that may follow the dummy protocol (TCP, ICMP, etc.). Here's the code I have: /* dissector_try_port() call for the dummy protocol */ ip_dissector_table = find_dissector_table("ip.proto"); next_tvb = tvb_new_subset(next_tvb, [macro for dummy proto length], -1, -1); dissector_try_port(ip_dissector_table, hf_[*it* field that is a copy of ip.proto's], next_tvb, pinfo, tree); But I assume nothing is matching because no protocols show up after the dummy protocol in the packet details window. -Scott
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Current thread:
- Sub_dissectors assertion failed Scott (May 20)
- Re: Sub_dissectors assertion failed Guy Harris (May 20)
- Re: Sub_dissectors assertion failed Scott (May 21)
- Re: Sub_dissectors assertion failed Guy Harris (May 21)
- Re: Sub_dissectors assertion failed Scott (May 21)
- MacOSX snow leo integration H.sivank (May 22)
- Re: MacOSX snow leo integration H.sivank (May 22)
- Re: MacOSX snow leo integration Stig Bjørlykke (May 22)
- Re: MacOSX snow leo integration H.sivank (May 22)
- Re: MacOSX snow leo integration H.sivank (May 22)
- Re: MacOSX snow leo integration Guy Harris (May 22)
- Re: MacOSX snow leo integration H.sivank (May 22)
- Re: MacOSX snow leo integration Guy Harris (May 22)
- Re: MacOSX snow leo integration H.sivank (May 23)
- Re: MacOSX snow leo integration Guy Harris (May 24)
- Re: Sub_dissectors assertion failed Scott (May 21)
- Re: Sub_dissectors assertion failed Guy Harris (May 20)